[Brewfixer]

Not sure if this is normal and certainly does not seem normal to me but every time I shut the boat motor off the RPM gauge stays at 500-800 RPMs and will stay like that until I start her again next time. I don't remember this last year but I don't know for sure...

Is this something to worry about or nuisance issue?

[doaclnr]

If it works I wouldn't worry about what it does when its off...

[Fletch2]

Had the same on a previous boat. Explained to me that the potentiometer finds its own level but is zeroed when the ignition is switched on and signal received by the tacho. Could have been a mechanic trying to baffle me though

[ColoradoDiablo]

Try spinning the selector switch on back , and resetting to 8 cyl. Brew
If you do a search on tach or tachometers , you will find more info on the cause and process.

[Hudson River Steve]

There is a weak magnet built into the air core meter movement that is supposed to return the gage back to 0 with no power. Does your gage go to zero when power is applied but the motor is not running? Do you have anything with a strong permanent magnet located near the tach?

[Motoxxx43]

Our Bass Tracker and my buddy's boat do the same thing. They work like they are suppose to when running

Sent from my DROID RAZR HD using Tapatalk

[Brewfixer]

Originally Posted by Hudson River Steve

There is a weak magnet built into the air core meter movement that is supposed to return the gage back to 0 with no power. Does your gage go to zero when power is applied but the motor is not running? Do you have anything with a strong permanent magnet located near the tach?

Ha! I think your on to something... one of my Memphis 12" subwoofer is directly under the console... Ironically my compass has never worked but I am guessing that the subwoofer wouldn't let that work either. Interesting I just noticed the RPM issue but have had the Subwoofer installed there 4 years now.

Hmmm... Anyway to shield this from the sub without adding a lot of weight?

[Hudson River Steve]

As long as the tach operates normally with the ignition turned on...I would just leave it alone. It would be rather difficult to make a magnetic shield over such a strong magnet. You would need to use a good magnetic conductor like iron which rusts or even better a mu-metal alloy which is expensive and difficult to source. At least you know what's going on now.